Air brake control system



Ndv. 16, 1937. D. F. SEARLE 2,099,453

AIR BRAKE CONTROL SYSTEM Filed April 12, 1937 2 Sheets-Sheet 1 W INVENTOR:

8 DUDLEY F. SEARLE AT TCRNEY.

Nov. 16, 1937. D. F. SEARLE AIR BRAKE CONTROL SYSTEM Filed April 12, 1937 2 Sheets-Sheet 2 INVENTOR: DUDLEY F. SEARLE ATTORNEY Patented Nov. 16, 1937 UNETED STATES ,ddtAStB FAT! QFQE 7 Claims.

This invention relates to improvements in power brake control systems and more particularly to brake systems for tractor and trailer com binations.

Among the objects of the invention is to automatically and fully apply and lock the trailer brakes in the event of the trailer becoming accidentally uncoupled from the tractor.

Another object is to obviate the necessity for relying upon the equipment being leakproof in order to hold the brakes fully applied after the trailer breaks away.

Another object is to enable the use of the automatic brake lock as a parking lock operable at the will of the driver.

Other objects and advantages appear as this description progresses.

In this specification and the accompanying drawings the invention is disclosed in its preferred 20 form. It is to be understood, however, that it is not limited to this form because it may be embodied in other forms within the spirit of the invention as defined in the claims following the description. 7

In the accompanying two sheets of drawings:

Figs. 1 and 2, to be read in conjunction with each other, are schematic diagrams principally in side elevation illustrating a brake system constructed in accordance with this invention.

Fig. 3 is a vertical section of the triple valve controlling the application of the brakes.

Fig. 4 is a similar view of the brake lock and its control valve.

Fig. 5 is a horizontal section of the valve for 35 manually controlling the operation of the brake lock.

In detail, the construction illustrated in the drawings, referring more particularly to Figs. 2 and 4, comprises the power chamber A on the 40 trailer formed by the shells I and 2 having their,

opposed flanges bolted together with the flexible diaphragm 3 therebetween. The pull rod 4 is attached to the diaphragm 3 in the usual manner and has its opposite end operatively connected to the lever 5 pivoted on the rod 6. The lever 5 controls the brake system of the trailer by the usual means (not shown).

The hose '1 connects the interior of the shell I to the triple valve B. The opposite side of the triple valve B is connected to the pressure reservoir C by the hose 8. When the brake system is in the normal released condition, the triple valve B is closed to the reservoir C. The power chamber A remains at atmospheric pressure until the triple valve B provides communication therefrom to the reservoir C. The reservoir C is connected through the pipe 9 on the trailer, the detachable coupling I between the trailer and the tractor, and the pipes H, II on the tractor .to a suitable source of pressure. In the present instance, the subatmospheric pressure of the intake manifold I2 of thecombustion motor is utilized.

The check valve I3 is interposed in the pipe 9 and prevents loss of pressure from the reservoir C should the coupling be broken. The check valve I4 is interposed in the pipe II and prevents fluctuations of pressure within the intake manifold I2 from being transmitted to the brake control system and adversely affecting its operation. The plug valve D is interposed between the pipes H, II on the tractor for purposes later to be described. It is open to permit unobstructed flow of pressure between the pipes II, II' throughout the normal operation of the system.

The triple valve B (see Fig. 3) comprises the body I having the base portion I6 with the lateral outlets I7 and I8 therein connected to the chamberA and the reservoir C respectively, as in Fig. 1. These outlets have the throats l9 and leading upwardly therefrom and discharging into the interior of the body I5. Theentrance of the throat 26 is surrounded by the annular valve seat 2|, with which the disc valve 22 is normally engaged, cutting off the reservoir outlet I8 from communication with the interior of the body I5. The valve 22 is held in seated position by the pressure differential against its opposite sides.

The passage 23 communicates with the throat I9 and leads downwardly through the base I6 to the atmosphere. The air cleaner 24 is attached to the base I6 and has the fibrous filter 25 therein to prevent the entry of dirt into the passage 23. The disk valve 26 has the stem 21 slidable within the tube 28 centrally located within the base I6. This valve is adapted to cooperate with the seat 29 to close the passage 23 from communication with the'atmosphere. The spring 26' expands between the air cleaner 24 and the valve 26 and urges the valve into engagement with the seat 29. The diaphragm 30 is interposed between the abutting flanges of the body I5 and the top 3| bolted thereto. The central portion of the diaphragm 29 is clamped between the discs 32, 32 by the nuts 33 and 34 threaded on the plunger 35. The lower portion of the plunger 35 is slidable within the tube 28 and operatively engages the top of the stem 21; The arm 36 is fixed on the plunger 35 and slidably engages the stem 31 of the disk valve 22. The cotter pin 38 is provided in the stem 31 above the plane of the arm The diaphragm 4| is interposed between the body 39 and the cover 43. The body has the outlet 42 which is connected by the pipe 43 to the pipe 9 between the reservoir C and the check valve |3.

The outlet 44 in the cover 40 is connected by the pipe 45 to the pipe 9 on the opposite side of the check valve l3, see Fig. 1. Since equal pressures normally exist on opposite sides of the checkvalve l3, there is usually no pressure differential applied against the diaphragm 4|.

The top 3| has the cavity 46 in the upper portion thereof. The opening 41 in the hollow body 35 is adapted to communicate with the cavity 46 and is. surrounded by the seat 48. The disc valve 4% is adapted tocooperate with the seat 48 and is attached to the diaphragm 4| by the plunger 50 which is screwed into the head 5|. The spring 52 in the recess 53 in the top 3| exmade against the disc valve 49 and seats it'at 48. The" passage 54 provides communication between the interior' of the top 3-| above the diaphragm 29 and the cavity 46; The valve seat 55 encircles the top of the recess 53. The valve 49 is adapted to seat at 55 when moved downwardly by the diaphragm 4| cutting off the passage 54 from communication with the interior of the recess 53; The passage 56 leads laterally from the recess 53 and is connected through the pipe 57, the detachable coupling 57, and the pipe 5'! to the manual control valve E; see Fig. 1. This valve is connected to the intake manifold I2 through the pipe M. It communicates with the atmosphere through the air cleaner E. Thecontrol valve E'is conventional in construction and operation. Reference may be had to the control valve disclosed i'n' my co-pending application #124,621 which is particularly suited for use in conj unctiori with thepresent' system.

The brake lock comprises the plate 58'bolted.

on to" the chamber A, (see'Fig'. 4). The" pawl 60' is pivoted at 6T on the yoke 62 extending downward from the plate 581 It is engageablewith the under-cut ratchet teeth 63 which are provided in the underside of the rod 4'. The collapsible cup 56 has its margins sealed to the plate 58 by the ring 65 bolted thereto. It is operatively connected to the pawl 60. by the-clevis 51.

The plate 58 has the large opening 68' therethrough registering with the interior of the colla'psible' cup 54. The base of' the control unit" 69' is fixed on the p1a'te58-above the opening 58 by the bolts 65. The control unit is similar to that described in connection with the triple valve B. It comprises the base 69' having the hollow'body l5 bolted thereon. The top of the body It is closed by the cover 11-. The diaphragm 1-2 is interposed between thebody l and thecover. H. The outlet pipes'l3 and I4 lead from thebody l0 and the cover ll respectively on-opposit'e sides of the diaphragm 12*. They are connected to the pipes 43 and 45 respectively which lead to the pipe 9 on opposite sides ofthe check valve l3. This'provid'es normally equal pressures on the 0pposite sides of the diaphragm l2.

The discvalvel is connected to the diaphragm l2 bythe stem 16. The valveis normally seated at ll cutting off communication between the cavity i8 and the" interior of the body 10. The passage 19' provides communication between the cavity l8 and the collapsible cup 54. The passage 35 leads off from the recess l8 and communicates with the atmosphere through the air cleaner 8|. The seat 82 is adapted to be engaged by the valve 75 to cut off the passage 85 from communication with the recess 18.

The air brake control system operates substantially as follows:

The control valve E is operated in the usual manner to establish subatmospheric pressure in the pipe 51. This pressure will vary with the extent of the brake application desired. It is transmitted through the passages 56 and 54 to the space withinthe top 3| above the diaphragm 3B.

As previously described, atmospheric pressure is maintained below the diaphragm 35 when the system is in normal inoperative condition. The subatmospheric pressure in the region above the diaphragm 33 consequently expands the diaphragm upward and raises the plunger 35 attached thereto. The arm 38 then engages the cotter pin-38; lifting the stem 3?, and unseating the diskvalve'22;

Communication is provided between the power chamber A and-the pressure reservoir C through the hose 7, the unseated' valve 22, and the hose ii. As-the pressure falls within the power chamber A, the diaphragm 3 contracts, pulling the rod 4 and swinging the lever 5 to apply the trailer brakesin the usual manner. The pressure in the reservoir C is maintained approximately constant during the application of the brakes by reason of its connection with the intake manifold 5 2 through thepipesfl and When the absolute pressure within the power chamber A and the body l5 of the triple valve B falls to the pressure previously established in the pipe 575 by'the operation of the control valve E; the diaphragm- 35- recedes and assumes the position shown'in Fig. 3 as soon as the pressure on its opposite sides becomes equal. This allows the valve 22 to; drop down into" engagement" with its seat 745". The power chamber A is then cut off from communication with the reservoir (land has itspre'ssure; rendered constant; The brakes are thus held'applied to an extent which depends upon. the pressure which has been established in the pipei'l. by the operation of the control valve E.

Should it be desired to apply the brakes to an additional-extent; the control'valve E is operated to further reducethe absolute pressure in;the-pipe ET. 'The; diaphragm 30 then againrises' and unseats the valve 22, reestablishing communication between the: power chamber'A. and the reservoir C; The absolute pressure within the power chamer A is then reduced until the pressure on the opposite sides of'the diaphragm 38 becomes equal when the'valve 22' is again seated.

To'release'the brakes, the valve E'isoperated to establish atmospheric pressure in the pipe 51. The: diaphragm: 29 then sinks in'to'the region of subatmcspheric pressure existing therebeneath. This causes the plunger 35 to push the stem 21 downward andunseats the valve 25. Atmospheric pressure then flows throughthe air cleaner 24, past theunseated valve 23, through the passage 23, into the body l5, and to thepower chamber A. The increased pressure within the chamber A releases thebrakes in the usual manner. When the pressure within the body |5 rises to atmospheric, the pressure on the opposite sides of the diaphragm 35 has become equal. The diaphragm then'rises' and assumes the position shown in Fig. 3' allowing'the'spring 26' to close the valve 25. The systemis now in normal released condition.

In the event of the trailer breakingaway from the tractor, the couplings-Ill and 51' between phragm is immediately depressed into'the region of subatmospheric pressure existing therebeneath.

This disengages the valve 49 from the seat 48-and seats it at 55. This cuts off' the pipeB'I 'from communication with the interior of the top 3!. The space above the diaphragm 33 now communicates with the reservoir C through the opening 41 'and the pipe 43. The establishment of the subatmospheric reservoir pressure above the diaphragm 33 raises the plunger 35 unseating the valve 22 and allowing the chamber A to be evacuated until it reaches the pressure of the reservoir C, thus applying the trailer brakes to their fullest I extent. The valve 22 cannot-close until the pressure'within the chamber A'is thus reduced to the pressure of the reservoir, because the diaphragm 30 cannot assume the position shown in Fig. 3 until the pressure on its opposite sides has become equal.

As previously described, the pipes I3 and I- I are connected to the pipes 43 and respectively.

Thus breaking the coupling II] also allows the 'flow of atmospheric air into the interior of the cover II. The pipe I3 remains at the subatmospheric pressure of the reservoir C. The diaphragm I2 is consequently depressed, and unseats the disk valve I5 from its seat I1, and engages it against the opposed seat 82. This cuts off the interior of the collapsible cup 64 from communication with the atmosphere through the passages I9 and 80 and the air cleaner ill. The collapsible cup is I evacuated by its communication with the reservoir C, through the passage I9, past the valve seat Ti, and through the pipe I3. The collapse of the cup 64 due to its evacuation raises the pawl 60 into engagement with the ratchet teeth 63 in is thus locked against disengaging therefrom. 7

Consequently, even though the pressure within the reservoir C might rise to atmospheric, the condition of the trailer brakes would be unaffected, since continuance of the evacuated condition of the collapsible cup at is now unnecessary to maintain the pawl 33 engaged in the ratchet teeth 63.

When the tractor is again coupled to the trailer, the valve E is operated to apply the brakes fully. The rod 4 then moves to the left slightly. This releases the nose of the pawl 6!! from locked engagement with the undercut ratchet teeth 63 and enables the spring I5? to expand and completely disengage the pawl EIB from the ratchet teeth.

The emergency locking device is capable of use as convenient means for locking the trailer brakes when parking. To this end the plug valve D is interposed between pipes I I and I I leading to the intake manifold I2.

This valve is illustrated in detail in Fig. 5. It consists of the body 85 having the tapered plug 86 therein. The port 81 provided through the plug 83 normally allows unobstructed flow of air through the valve.

In looking the trailer brakes for parking, the brakes are first applied in the usual manner by the operation of the valve E which controls the triple valve B in the manner thereinbefore described. -The plug 86 is then rotated by the handle 38 (see Fig. l) to remove the port 81 from registry with the outlets of the body 85. The groove 83 provides communication between the atmospheric port 96 and the pipe II. This permits the flow of atmospheric air into the pipe I I as far asthe check valve l3, which automatically' closes. This is tantamount to breaking the coupling l9 since it establishes atmospheric pressure in the pipe i4 and operates the brake look exactly in the manner it was operated in the case of the trailer breaking away as above described. r

The parking lock is released by restoring the plug valve D to its initial position illustrated in Fig. 5, and then fully applying the trailer brakes by operation of the control valve E. This allows release of the pawl 53 from the undercut ratchet teeth 63.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A'power brake system including a source of fluid pressure; a pressure reservoir; a means connecting said reservoir to said source; means for preventing loss of pressure from said reservoir through the connecting means; fluid pressure means for actuating the brakes connected with said'reservoir; a valve interposed between said actuating means and said reservoir; means for locking said brake actuating means in operative position; control means connected to said couplirig-and adapted to open said valve and to operate said locking means when the pressure in said connecting means falls below a given point.

2. A power brake system for tractor and trailer combinations including a source of subatmospheric pressure on said tractor; a pressure reservoir on said trailer; breakable means connecting said reservoir with said source; means for preventing loss of pressure from said reservoir through said connecting means; brake actuating means operatively connected with said reserve tank; a valve interposed between said brake actuating means and said reservoir; means controlled by the fluid pressure in said breakable connecting means, adapted to open said valve should said connecting means be broken; means for locking said brake actuating means in operative position; and means adapted to operate said locking means should said coupling be broken.

3. A power brake system for tractor and trailer combinations including a source of subatmospheric pressure on said tractor; a pressure reservoir on said trailer; breakable means connecting said reservoir to said source; means for preventing loss of pressure from said reservoir through said connecting means; brake actuating means operatively connected to said reservoir; a valve interposed between said actuating means and said reservoir; means for opening said valve should said connecting means be broken; means valve interposed between said lock operating means and said reservoir and adapted to be opened by the breaking of said connecting means.

4. A power brake system for tractor andtrailer combinations including a source of subatmospheric pressure on said tractor; a pressure reservoir on said trailer; breakable means connecting said reservoir to said source; means for preventing loss of pressure from said reservoir through said breakable connecting means; brake actuating means operatively connected with said reservoir; a valve interposed between said actuating means and said reservoir; pressure controlled means for opening said valve; means for admitting pressure from said reservoir to said pressure controlled means should said connecting means be broken; means for locking said brake actuating means in operative position; pressure operated means for actuating said locking means; means for admitting pressure from said reservoir to said lock actuating means and rendered operative by the change of the pressure in said breakable connecting means to atmospheric; and a valve on said tractor adapted to cut off said breakable connecting means from communication with said pressure source and adapted to admit atmospheric pressure to said connecting means. a

5. A power brake system for tractor and trailer combinations including a source of subatmospheric pressure on said tractor; a pressure reservoir on said' trailer; a breakable coupling connecting said reservoir to said source; a check valve interposed between said reservoir and said coupling and adapted to prevent loss of pressure from said reservoir through said coupling; brake actuating means connected to said reservoir; a valve interposed between said brake actuating means and said reservoir; means for opening said valve should the pressure in said coupling become atmospheric; means for locking said brake actuating means in operative position;

6 A.power=b-rake system for tractor and trailer combinations including a source of subatmosphericpressure on said tractor; a reservoir to said source; means-for preventing loss of pressure from said reservoir through said coupling; brake actuating means connected to said reservoir; a valve interposed between said reservoir and said brake actuating means; means for opening said valve should said coupling be broken; a pawl adapted to lock said brake actuating means in operative position; means for locking said pawl in engagement with said brake actuating means should said brake actuating means begin to move toward release position; subatmospheric pressure means for actuating said pawl; and means operated by the breaking of said coupling for admitting subatmospheric pressure from said reservoir to said pressure means.

7 A power brake system including a source of subatmospheric pressure, a pressure reservoir; means connecting said reservoir with said source and 'having a breakable coupling associated therewith; means for preventing loss of pressure from said reservoir through said coupling; subatmospheric pressure means connected with said reservoir for actuating the brakes; a valve interposed between said actuating means and said-reservoir; means for locking said brake actuating means in operative position; control means adapted toopen said valve and operate said looking means when the pressure in said coupling falls below a given point.

DUDLEY F. SEARLE. 

